Sedation Flashcards
What are the techniques called when there is LOC?
Deep sedation
GA
What is the definition of sedation?
A technique using drug/s to produce a state of CNS depression enabling treatment to be carried out but retain verbal contact (or normal means of contact) with the patient throughout the sedation period. The drugs used to carry out conscious sedation should have a wide safety margin to render LOC unlikely
What are the medical indicators for sedation?
Conditions which are aggravated by the stress of dental treatment eg IHD Hypertension Asthma Epilepsy Psychosomatic illness UC Crohns Conditions which affect co-operation Parkinson's/learning difficulties/spasticity disorders
What are the categories that indicate sedation is required?
Medical
Psychosocial
dental
What are the psychosocial indications for sedation?
Phobia
Gagging
Persistant fainting
Idiosyncrasy to LA
What is a phobia?
an irrational and uncontrollable fear which is related to a specific object or situation
it is persistant despite avoidance of the provoking stimulus and has a direct effect on the patients lifestyle
What are the causes of dental anxiety?
trauma: primary traumatic experience/may be cumulative Transference: parental/peers helplessness dress code invasion of body orifice lack of communication age development SES Gender
What are the dental indications for sedation?
surgical extraction of wisdom teeth
ortho extrcation
implants
(unpleasant situations)
What are the broad categories for the contra-indications to sedation?
Medical
social
Dental
What are the medical contra-indications to sedation?
severe uncontrolled systemic disase severe enta or physical handicap svere psychatric problems narcolepsy hypthyroidism
What are the social contr-indications to sedation?
Unwilling
unco-operative
unaccompanied
Very old
What are the dental contr-indications to sedation?
Procedure too difficult for LA alone
Procedure too long
spreading infection (airway threatening)
Procedure too traumatic
What are the medical contr-indications to sedation with benzodiazepines?
Intracranial pathology COPD Myasthenia Gravis Hepatic insufficiency Pregnancy and lactation
What are the medical contra-indications to inhalational sedation?
blocked nasal airway
COPD
Pregnancy
What are the requirements of an ideal sedative agent?
Anxiolysis Analgesic No effect on CNS No effect on respiratory Not metabolised Easy and quick to change level of sedation Reversible No-interaction with other drugs Long shelf life Cheap
What is the definition of pharmacodynamic?
the effect of the drug on the body
What is the definition of pharmacokinetic?
what the body does to the drug
T/F the pharmacodyanmics of BZD drugs are the same for all
T
T/F the pharmkinetic action of the BZD are the same?
F. they have different potencies (receptor affinity), half lives and presence of active metabolites
What are the actions of BZD with increasing doses?
Anxiolysis, Anticonvulsion, slight sedation, amnesia, intense sedation, muscle relaxation, anaesthesia (in order of effect of increasing dose)
What is the first effect of sedation?
anxiolysis
What is sedation?
decreased response to constant stimuli
Which two drug groups are anticonvulsant?
sedatives and hypnotics
What is the effect of BZD on amnesia?
IV BZD gives anterograde amnesia, most intense for 20-30 minutes however this has an unpredictable duration
T/F BZD are analgesic?
F
they may influence the response to pain but they are not analgesic
What is the mechanism of action for BZD?
two mechanisms of action
- BZD act on GABA receptors to enhance the effect of GABA
- mimic the effect of glycine
Where are the GABA receptors located?
cerebral cortex
where are the glycine receptors?
brainstem and spinal cord
What effect do BDZ have on motor circuits ?
they act as anticonvulsants
What is the effect of BDZ on the cortex?
they cause sedation
What peripheral sites have BZD receptors?
myocardium
Kidney
Adrenals
What are the side effects of BZD on respiration?
depression
What are the side effects of BZD on CNS?
depression
What are the side effects of BZD on muscle?
relaxation
What are the side effects of BZD on cerbral response to CO2?
decreases repsonse to CO2
T/F BZD interact synergiystically with opiods?
T
In which group of patients are the effects of BZD enhanced in?
those with chronic bronchitis
What is the effect of BZD on the cardiovascualr system?
they cause a reduction in BP by reducing vascular resistance and heart rate then increases via the barareceptor reflex
T/F BDZ have a direct effect on the baroreceptor reflex
F
Which drugs to BDZ interact with?
ketoconazoles, erhythro with midalzolam
opioids
CNS depressants
What is the effect of BZD with CNS depressants?
enhanced resp depression
List the side effects of BZD
sexual fantasy respiratoy depression drug interactions decreased cerbral response to CO2 muscle and CNS relaxation
When do sexual fantasies begin to occur?
with midazolam doses of more than 0.1mg/kg
who do sexual fantasies occur more in, males or females?
equal across both genders
WHat are the unwanted side effects of BDZ?
tolerance
dependance
What does the term tolerance refer to?
patients that are taking BDZ become tolerant to their effects
What does the term dependance refer to?
long term oral administration causes addiction and patients will experience withdrawl reactions when they stop taking BZD
How long does it take people to become dependant on midazaolam?
this can be activated after a single administration
How can an actute withdrawl occurr following BDZ use?
by using BZD antagonists
How can BDZ be adminstered?
orally
IV
Transmucosal
T/F midazolam is water soluble
T
T/F midazolam is only water solubale above pH 4.0
F below pH 4.0
What group of BZD does midazolam come under?
imadazoBZD
at physiological pH is midaz water or lipid soluble?
lipid
What is the consequence of midazolams lipid solubulity ?
it can cross the BBB
t/F midazolam has no rebound sedation
T
What is the half life for midazolam?
90-150mins
T/F midazolam has active metabolites?
T
What is the name of the active metabolote of midazolam?
hydroxymidazolam
WHat is the half life of hydroxymidazolam?
1.25hours
What size ampoule and why do we use of midazolam?
5mg/5ml
this is easier to titrate
where is midazolam metabolosed?
in the liver but also extra hepatic
What is the effect of liver disease on midazolam half life?
not a great affect when compared to other BDZ
How does renal disease affect midazolam pharmakokinetics?
it has not effect in an acute administration
What is the name of the BDZ antagonist used?
Flumazenil anexate
What type of BDZ is Flumazenil-Anexate?
It is an imadazoBDZ
what are the features of FLumazenil?
it has a high receptor affinity and low intrinsic action
How does Flumazenil work?
It competitively displaces active BDZ from receptor sites
What is the half life of flumzenil?
53 mins
Why is there residual sedation following usage of flumazenil with midazolam?
because the half life of flumazenil is 53 mins comapred to midazolam which is 90-150mins.
What are the indications to using flumazenil?
reversal of sedation in an emergency
What are the contraindications to using fluamzenil?
allergy to BDZ
pateints taking BDZ in epilepsy
Patients that are dependant on BDZ
Which agent is used for inhalational sedation?
Nitrous Oxide
What are the clinical effects of Nitrous Oxide?
- causes CNS depression without respiratory or vasomotor paralysis
- Analgesic
What are the clincal effects of NO?
Euphoria
Anxiolysis
Analgesia
Time compression
By what mechanism does NO produce analgesia?
same mechanism as opiods
What are the physical properties of NO?
colourless sweet smelling non irritant one and half times heavier than air (specific gravity 1.53) supports combustion
What can you not use in combination with NO?
elctrosurgery
How soluble is NO in blood? and what effect does this have on how it is carried in the body?
poorly
it is carried in simple solution
T/F there is rapid equilibration of NO between blood and air?
T
Under what pressure does NO exist as a liquid?
800psi
43.5bar
21degrees celcius
How potent is NO compared to other anaesthetic gases?
least potent
How is potency in terms of drugs expressed? And what does this mean
MAC
minimal alveolar concentration
This is the inspired concentration if an agent which will abolish the response to a surgical stimulus in 50% of pateints
T/F NO is eliminated as an unchanged drug through the lungs?
T
What are the side effects of NO pollution?
decreased fertility
decreased red blood cell synthesis via vitamin B12
Neurological effects
Liver
What must be in place when using NO in sedation?
You must have a scavenging system
What is anterograde amnesia?
Where there is loss in ability to create memories after the event has taken place